Fourteen patients with Wolff-Parkinson-White syndrome (W-P-W) and 2 pa-tients with atrioventricular node dual pathway (AVNDP) underwent radiofrequency current abla-tion. There were 14 accessory pathways located on the left side of the heart (11 left-free wall. 1 left postseptal, 1 left postlateral and 1 left midseptal), 2 on the right side (1 right anteroseptal, 1 right free-wall). In patients with left side pathways, ablation was attempted via a catheter posi-tioned in the left ventricule directly below the mitral annulus. In patients with right side accessory pathways , the ablation catheter was positioned in the atrial aspect of tricuspid annulus. Accessory pathway conduction was permanently abolished in all the patients (100% ). 2 patients with AVNDP were also successfully ablated by blocking the slow pathways. Plasma CK-MB , SGOT and LDH in-creased moderately in 9 patients (52. 9%) and decreased to normal level after 3～4 days. No severe complications were noted. Conclusion: catheter radiofrequncy current ablation may be an effective and safe therapeutic modality for patients with refractory tachycardias mediated by these path-ways.